In recent years, there have been an increasing number of applications for video-on-demand type services, for example, including video conferences, digital video broadcasting, and streaming of video content via the Internet, and these applications depend on transmission of video information. At the time of transmission or recording of video data, a considerable amount of data is transmitted through a conventional transmission path of a limited bandwidth or is stored in a conventional recording medium with limited data capacity. In order to transmit video information through a conventional transmission channel and store video information in a conventional recording medium, it is essential to compress or reduce the amount of digital data.
Thus, a plurality of video coding standards have been developed for compressing video data. Such video coding standards include, for example, International Telecommunication Union Telecommunication Standardization Sector (ITU-T) standards denoted as H.26x, and the ISO/IEC standards denoted as MPEG-x. The most up-to-date and advanced video coding standard is currently the standard denoted as H.264/AVC or MPEG-4/AVC (refer to Non Patent Literature 1).
The coding approach which serves as a basis for these standards is based on prediction coding including major steps to be shown the following (a) to (d). a) In order to perform data compression on a block level for each of the video frames, the video frame is divided into blocks of pixel. (b) By predicting each of the blocks from the already coded video data, temporal and spatial redundancy is specified. (c) By subtracting the prediction data from the video data, the specified redundancy is eliminated. (d) By Fourier transform, quantization, and entropy coding, the remaining data (residual blocks) are compressed.